1. Field of the Invention
The present invention relates to an electret condenser microphone (referred to as an “ECM” hereinafter) comprising a metal capsule having a top surface provided with sound receiving holes, a diaphragm, a back electrode plate that faces either one of surfaces of the diaphragm and that is provided separately from the capsule, and an electret layer formed on the back electrode plate or the diaphragm. The diaphragm, the back electrode plate and the electret layer are all mounted inside the capsule.
2. Description of the Related Art
The ECM is applied to a wide variety of electronic devices including mobile phones, PDAs, digital cameras, etc. Since the ECM is a very small component, the reflow mounting technique, for example, is often used in mounting the ECM on the various devices, in which solder is applied on a circuit board to provide the ECM, and then the circuit board is heated to be fixed with solder. In the process of reflow mounting, the ECM is sometimes transported onto the circuit board by using a suction-type transporting device in order to expedite the process for mounting the ECM on the circuit board.
As shown in FIG. 6, many of the conventional ECMs include a sound hole formed in the center of a top surface of a capsule comprising a box-shaped member. Thus, when using the suctioned-type transporting device, suction force is applied on any portion other than the sound hole to transport the ECM to a desired position on the circuit board so as not to damage the diaphragm or the like mounted inside the ECM. (see Japanese U.M. Registration No. 2,548,543, FIG. 1)